Cold row encapsulation for server farm cooling system

ABSTRACT

Apparatuses, methods, and systems directed to efficient cooling of data centers. Some embodiments of the invention allow encapsulation of cold rows through an enclosure and allow server fans to draw cold air from the cold row encapsulation structure to cool servers installed on the server racks. In other particular embodiments, the systems disclosed can be used to mix outside cool air into the cold row encapsulation structure to cool the servers. In some embodiments, the present invention involves using multiple cold row encapsulation structures to cool the servers installed on the racks.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 11/757,864 filed Jun. 4, 2007, which is incorporated byreference herein for all purposes.

TECHNICAL FIELD

The present disclosure relates generally to cooling systems for datacenters.

BACKGROUND

The rapid growth of Internet services such as Web email, Web search, Website hosting, and Web video sharing is creating increasingly high demandfor computing and storage power from servers in data centers. While theperformance of servers is improving, the power consumption of servers isalso rising despite efforts in low power design of integrated circuits.For example, one of the most widely used server processors, AMD'sOpteron processor, runs at up to 95 watts. Intel's Xeon server processorruns at between 110 and 165 watts. Processors are only part of a server,however; other parts in a server such as cooling fans and storagedevices consume additional power.

Servers are typically placed in racks in a data center. There are avariety of physical configurations for racks. A typical rackconfiguration includes mounting rails to which multiple units ofequipment, such as server blades, are mounted and stacked verticallywithin the rack. One of the most widely used 19-inch rack is astandardized system for mounting equipment such as 1U or 2U servers. Onerack unit on this type of rack typically is 1.75 inches high and 19inches wide. A server that can be installed in one rack unit is commonlydesignated as a 1U server. In data centers, a standard rack is usuallydensely populated with servers, storage devices, switches, and/ortelecommunications equipment.

A data center room should be maintained at acceptable temperatures andhumidity for reliable operation of the servers, which typically havecooling fans that draw air through the chassis for cooling. The powerconsumption of a rack densely stacked with servers powered by Opteron orXeon processors may be between 7,000 and 15,000 watts. As a result,server racks can produce very concentrated heat loads. The heatdissipated by the servers in the racks is exhausted to the data centerroom. The heat collectively generated by densely populated racks canhave an adverse effect on the performance and reliability of theequipment in the racks, since they rely on the surrounding air forcooling. Accordingly, heating, ventilation, air conditioning (HAVC)systems are often an important part of the design of an efficient datacenter.

A typical data center consumes 10 to 40 megawatts of power. The majorityof energy consumption is divided between the operation of servers andHVAC systems. HVAC systems have been estimated to account for between 25to 40 percent of power use in data centers. For a data center thatconsumes 40 megawatts of power, the HAVC systems may consume 10 to 16megawatts of power. Significant cost savings can be achieved byutilizing efficient cooling systems and methods that reduce energy use.For example, reducing the power consumption of HVAC systems from 25percent to 10 percent of power used in data centers translates to asaving of 6 megawatts of power which is enough to power thousands ofresidential homes.

In a data center room, server racks are typically laid out in rows withalternating cold and hot aisles between them. All servers are installedinto the racks to achieve a front-to-back airflow pattern that drawsconditioned air in from the cold rows, located in front of the rack, andejects heat out through the hot rows behind the racks. A raised floorroom design is commonly used to accommodate an underfloor airdistribution system, where cooled air is supplied through vents in theraised floor along the cold aisles.

An important factor in efficient cooling of data center is to manage theair flow and circulation inside a data center. Computer Room AirConditioners (CRAC) units supply cold air through floor tiles includingvents between the racks. In addition to servers, CRAC units consumesignificant amounts of power as well. One CRAC unit may have up to three5 horsepower motors and up to 150 CRAC units may be needed to cool adata center. The CRAC units collectively consume significant amounts ofpower in a data center. For example, in a data center room with hot andcold row configuration, hot air from the hot rows is moved out of thehot row and circulated to the CRAC units. The CRAC units cool the air.Fans powered by the motors of the CRAC units supply the cooled air to anunderfloor plenum defined by the raised sub-floor. The pressure createdby driving the cooled air into the underfloor plenum drives the cooledair upwardly through vents in the subfloor, supplying it to the coldaisles where the server racks are facing. To achieve a sufficient airflow rate, hundreds of powerful CRAC units may be installed throughout atypical data center room. However, since CRAC units are generallyinstalled at the corners of the data center room, their ability toefficiently increase air flow rate is negatively impacted. The cost ofbuilding a raised floor generally is high and the cooling efficiencygenerally is low due to inefficient air movement inside the data centerroom. In addition, the location of the floor vents requires carefulplanning throughout the design and construction of the data center toprevent short circuiting of supply air. Removing tiles to fix hot spotscan cause problems throughout the system.

SUMMARY

The present invention provides systems and methods directed to efficientcooling of data centers. In a particular embodiment, the presentinvention provides a cold row encapsulation structure comprising atleast one server rack port configured to interface with one or moreserver racks and a cooling module connected to the top surface of thecold row encapsulation structure. The server rack ports are configuredto engage the server racks such that a front face of the server racksinterface with the interior space defined by the cold row encapsulationstructure. In some embodiments, server racks ports and server racks aretightly connected by clamps and/or sealing gaskets to reduce air leakageinto and out of the cold row encapsulation structure.

Some embodiments of the invention utilize cooling fans of the serversinstalled on the racks to draw cold air from cold row encapsulationstructure from the front face of the server racks and to eject hot airfrom the back side of the server racks. Some embodiments of theinvention obviate the need for raised subfloors, and the fans and otherequipment for forcing cooled air into an underfloor plenum. The coolingmodule installed on top of the cold row encapsulation structure coolsthe hot air through cooling coils installed inside the cooling module.In some embodiments, cold water is used inside the coils to exchangeheat with hot air in the cooling module.

In one embodiment of the present invention, the systems and methods aredirected to cooling hot air inside the data center server cooling roomwithout introducing outside air. The hot air ejected by the server fansenters the cooling modules that may be located on top of the cold rowencapsulation structure. The hot air is cooled by the water basedcooling coils inside the cooling modules and the cooled air enters thecold row encapsulation structure through gravity and the lower pressurecreated inside the interior space of the cold row encapsulationstructure. Server fans draw cold air from the server rack portsconnected to the cold row encapsulation structure to cool the serversand eject hot air from the back side of the server racks.

In other embodiments of the present invention, the systems and methodsinvolve mixing outside cool air to cool the servers. In one embodiment,ceiling dampers in a data center may be controlled by a temperaturecontrol unit and opened up when the outside temperature reaches certainthreshold value. Outside air enters the data center and passes throughthe cooling module installed on top of the cold row encapsulationstructure. Server fans draw the cold air from the cold row encapsulationstructure. Hot air is exhausted to the outside by the ceiling exhaustfans. In some embodiments, to control the moisture in the air in thedata center server cooling room, especially when the outside air failsto meet the operating requirements for the servers and other equipment,humidifiers may be used to condition the outside air. In recent years,however, manufacturers of server equipment have significantly relaxedthe humidity requirements due to technological advancement.

The following detailed description together with the accompanyingdrawings will provide a better understanding of the nature andadvantages of various embodiments of the present invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example cold row encapsulation structureand an example cooling module.

FIG. 2 is a diagram showing an example cold row encapsulation structurewith integrated server racks and an example cooling module.

FIG. 3 is a diagram showing an example cold row encapsulation structurewith integrated server racks, an example server placed on one of theserver racks, and an example cooling module.

FIG. 4 is a diagram showing an example server with a server fan thatdraws cold air conditioned by an example cooling module.

FIG. 5 is a diagram showing an example data center server cooling roomwith a cold row encapsulation structure, a cooling module, exhaust fanson the roof, and a mixing chamber with dampers that controls the indoorand outdoor air circulation.

FIG. 6 is a diagram showing an example data center server cooling roomwith a cooling module that is integrated with a mixing chamber.

FIG. 7 is a diagram showing an example data center server cooling roomwith multiple cold row encapsulation structures and multiple coolingmodules, exhaust fans on the roof, and a mixing chamber with dampersthat controls the indoor and outdoor air circulation.

FIG. 8 is a diagram showing an example data center server cooling roomwith multiple cold row encapsulation structures and a cooling modulethat is integrated with a mixing chamber with dampers.

FIG. 9 is a diagram showing an example data center server cooling roomwith multiple cold row encapsulation structures and multiple coolingmodules, exhaust fans on the roof, and a mixing chamber with dampersthat is integrated with a cooling module.

DESCRIPTION OF EXAMPLE EMBODIMENT(S)

The following example embodiments and their aspects are described andillustrated in conjunction with apparatuses, methods, and systems whichare meant to be illustrative examples, not limiting in scope.

FIG. 1 illustrates an example cooling module 100 and an example cold rowencapsulation structure 106. The cold row encapsulation structure 106may have a frame, panels, doors, and server rack ports. A server rackport is an opening on the cold row encapsulation structure 106 that canbe connected to a server rack. The cold row encapsulation structure 106may be made of a variety of materials such as steel, compositematerials, or carbon materials that create a housing defining aninterior space including at least one server rack port that allows arack-mounted unit to interface with the interior space. In someembodiments, the cold row encapsulation structure 106 may be mounteddirectly to the floor surface and no raised floor is required in a datacenter cooling room for cooled air.

The cooling module 100 may be located and positioned on top of the coldrow encapsulation structure 106 and connected to the top surface of thecold row encapsulation structure 106. The cooling module 100 comprisesone or more cooling coils 102. Liquid passing inside the cooling coils102 is used to exchange heat with relatively hot air passing through thecooling module 100, thereby cooling the air. In one embodiment, thecooling module 100 further comprises an enclosure inside which thecooling coils 102 are located. The cooling module enclosure may have oneor more openings 104 through which air enter the enclosure. In someembodiments, the openings 104 may comprise air filters. The coolingmodule enclosure may have one or more openings connected to the topsurface of the cold row encapsulation structure 106, through whichopenings cold air exits the cooling module and enters the interior spacedefined by the cold row encapsulation structure.

In some embodiments, water is used inside the cooling coils 102 as heatexchangers. Water pumps, water cooling equipment, and associatedplumbing (not illustrated) supplies cooled water to the cooling coils102. In other embodiments, other types of liquid such as a water-glycolsolution, steam, or a refrigerant may be used inside the cooling coils102 as heat exchangers.

In some embodiments, the cooling coils 102 may be serpentine shapedlines of tubing. In other embodiments, the cooling coils 102 may be inother shapes such as straight lines of tubing. Depending on the size ofthe cold row encapsulation structure 106, the cooling requirements, thevelocity of air flow, and the physical characteristics of the coolingcoils 102, the number of cooling coils in the cooling module 100 mayvary. In one embodiment, two cooling coils are used inside the coolingmodule 100.

Since cold air is generally heavier than hot air, the cold air cooled bythe cooling coils 102 generally moves downward into the interior spacedefined by the cold row encapsulation structure 106 which may be locatedbelow and connected to the cooling module 100. The cold rowencapsulation structure 106 comprises an enclosure which defines aninterior space. The enclosure comprises at least one server rack port110 configured to interface with a plurality of server racks. The serverrack port 110 is configured to interface with the server racks such thata front face of the server racks intersects the interior space of thecold row encapsulation structure 106. In one embodiment, six standardserver racks may be connected to the server rack port 110. In anotherembodiment, twelve standard server racks may be connected to the serverrack port 110. In some embodiments, the server racks and the server rackports 110 may be connected together through one or more clamps 112. Inother embodiments, the server racks and the server rack ports 110 may beplaced next to each other. In some other embodiments, sealing materialssuch as gaskets may be used to tightly connect the server rack port 110and the server racks. The servers are installed into the racks toachieve a front-to-back airflow pattern that draws conditioned air infrom the cold row encapsulation structure 106 in the front, and ejectsheat out behind the racks.

In one embodiment, the cold row encapsulation structure 106 may comprisemore than one server rack port 110. A server rack port 110 may engage aserver rack such that the front face of servers or other devicesinstalled in the server interface with the interior space defined by thecold row encapsulation structure 106. This configuration achieves afront-to-back airflow pattern, where the cooling fans of the servers orother rack-mounted units draw air from the interior space and exhaustair heated by the processor(s) and other components out the back panel,as illustrated in FIG. 4. In some embodiments, the server rack and thecold row encapsulation structure may be substantially sealed;conditioned cold air inside the interior space of the cold rowencapsulation structure 106 is drawn by the server fans inside theservers to cool the servers. In other embodiments, the server rack andthe cold row encapsulation structure 106 are placed next to each otherso that conditioned cold air inside the interior space of the cold rowencapsulation structure 106 can be drawn to the servers by the serverfans inside the servers. The relatively hot air is circulated to thecooling module 100 on top of the cold row encapsulation structure 106and exchanges heat with the cooling coils 102. Cold air from the coolingmodule 100 sinks to the cold row encapsulation structure 106 and isdrawn to the back of the servers by server fans inside the servers. Insome embodiments, server racks are sparsely populated with servers andother equipment. Since servers and other equipment are stackedvertically within the rack, the scarcity may create open gaps to theinterior space of the cold row encapsulation structure. Cold air mayleak from the interior space of the cold row encapsulation structure106, and hot air may circulate back to the interior space, therebyreducing the cooling efficiency. To prevent air leakage, the gaps may beblocked by panels mounted to the server rack that prevent air fromescaping and entering the cold row encapsulation structure through thegaps.

In one embodiment, the cold row encapsulation structure 106 may furthercomprise stability control units 114 on the bottom. The stabilitycontrol units 114 may comprise components that are built to withstandseismic movements during natural disasters such as earthquakes. In someembodiments, the stability control units 114 may have devices forscrolling that can be quickly released to easily move the cold rowencapsulation structure 106. When stability control units 114 are used,the cold row encapsulation structure 106 may be raised from the ground.As a result, cold air may leak and hot air may enter from the bottomside of the cold row encapsulation structure 106. To prevent airleakage, in one embodiment, the bottom side of the cold rowencapsulation structure 106 may be enclosed by a panel that seals thebottom surface, on which panel the stability control units 114 may beattached.

In one embodiment, one or more doors 108 may be installed on theenclosure of the cold row encapsulation structure 106. The door 108 maybe opened and closed so that data center personnel may enter the coldrow encapsulation structure for a variety of tasks such as servermaintenance. The door 108 may be insulated to prevent cold air fromleaking out of the cold row encapsulation structure 106.

The dimension of the cold row encapsulation structure 106 can varyconsiderably depending on the desired number of server racks, thecooling requirements of the servers, and the like. In one embodiment,six to twelve standard server racks may be connected to respectiveserver rack ports 110 of the cold row encapsulation structure 106.Another six to twelve standard server racks may be connected to theserver rack ports on the opposite side of the cold row encapsulationstructure. The distance between the opposing server rack ports may be 4feet. The height of the cold row encapsulation structure 106 may be 12feet and the depth may also be 12 feet.

FIG. 2 illustrates an example cooling module 200, a cold rowencapsulation structure 206, and integrated server racks 208 and 210.The system in this example is similar to the one shown in FIG. 1 exceptthat the server racks are integral parts of the system. In thisembodiment, the connection and sealing between the cold rowencapsulation structure 206 and the server racks 208 and 210 are nolonger required since the server racks are part of the cold rowencapsulation structure 206. The servers may be installed into theintegrated server racks 208 and 210 to achieve a front-to-back airflowpattern. The front face of the integrated server racks 208 and 210intersects the interior space of the cold row encapsulation structure206. The server fans inside the servers draw cold air from the cold rowencapsulation structure 206 to cool the servers and blow out relativelyhot air from the back of the server racks. Hot air is then circulated tothe cooling module 200 through one or more openings 204 and exchangesheat with the one or more cooling coils 202. The cooling module 200 maybe located on top of the cold row encapsulation structure 206 and may beconnected to the top surface of the cold row encapsulation structure 206through an opening on the top side of the cold row encapsulationstructure 206 and the bottom side the cooling module 200. Cold airgenerally moves downwards, especially when server fans are drawing coldair from the cold row encapsulation structure creating lower airpressure in the interior space of the cold row encapsulation structure206.

FIG. 3 illustrates an example cooling module 300, cold row encapsulationstructure 302, server racks 304, and an example server 306 placed on aserver rack. The system in this example is similar to the one shown inFIG. 2. Conditioned cold air enters the cold row encapsulation structure302 through the cooling module 300 placed on top of the cold rowencapsulation structure 302. Server fans inside the server 306 drawconditioned cold air from the interior space of the cold rowencapsulation structure 302 and cools the server 306.

FIG. 4 illustrates an example cooling module 400, cooling coils 402,server 404 and server fan 406 inside the server 404. Conditioned coldair from the cooling module 400 and cooling coils 402 is drawn by theserver fan 406 and passes through the server 404 to cool the server.Relatively hot air is then blown out of the server 404 by the server fan406.

The cooling systems illustrated in FIGS. 1 and 2 can operate in aninterior space defined by a data center server cooling room, asdisclosed above, to draw air from the interior space, and provide cooledair to the interior of the cold row encapsulation structure 106. In someimplementations, however, the cooling systems may also operate inconnection with a data center cooling room that includes air flowcontrols that allow outside air to be used. FIG. 5 illustrates anexample data center server cooling room 500 with one or more ceilingexhaust fans 516, ceiling dampers 514 which controls outside air intake,a mixing chamber 518, and dampers 512 that control circulation of airentering into the mixing chamber 518. The cooling module 502 comprisesone or more cooling coils 504 and is connected to the mixing chamber518. The top surface of the cold row encapsulation structure 506 isconnected to the cooling module 502. Server rack ports 508 on theenclosure of the cold row encapsulation structure 506 are connected tothe server racks 510. The servers may be installed into the server racksto achieve a front-to-back airflow pattern. The front face of the serverracks intersects the interior space of the cold row encapsulationstructure 506. The server fans inside the servers draw cold air from thecold row encapsulation structure 506 to cool the servers and eject hotair server racks.

The server cooling room 500 may be operated in two modes. In one mode,no outside air is introduced to the server cooling room 500; the hot airejected from the servers is circulated back to the mixing chamber 518and the cooling module 502. In another mode, outside cool air isintroduced to the server cooling room 500. The ceiling dampers 514 areopen while the dampers 512 on the mixing chamber are closed. Outsidecool air passes through the cooling module 502 and enters cold rowencapsulation structure 506.

In one embodiment, the ceiling dampers 514 are closed and the dampers512 on the mixing chamber are open. Part of the hot air ejected by theservers is exhausted outside of the server cooling room 500 through theone or more ceiling exhaust fans 516; part of the hot air enters themixing chamber 518 through the open dampers 512. The hot air inside themixing chamber is drawn to the cooling module 502 and exchanges heatwith the cooling coils 504. Cold air then enters the cold rowencapsulation structure 506 through gravity and lower air pressureinside the interior space of the cold row encapsulation structure 506.

In another embodiment, the ceiling dampers 514 are open and the dampers512 on the mixing chamber are closed. The outside cool air enters themixing chamber 518 through the open dampers 514, passes through thecooling module 504, and sinks to the interior space of the cold rowencapsulation structure 506.

In some embodiments, the opening and closing of the dampers 512 and 514may be controlled by a temperature control unit. When the outsidetemperature reaches an appropriate level, the temperature control unitopens up the ceiling dampers 514 to allow outside air to enter the roomand closes the dampers 512 on the mixing chamber to prevent hot airejected from the server from entering the mixing chamber. When theoutside temperature is too hot for the server cooling room 500, thetemperature control unit closes the ceiling dampers 514 to preventintroducing hot outside air indoors, and opens up the dampers 512 toallow hot air ejected from the servers back to the mixing chamber.Utilizing outside natural cool air significantly reduces energyconsumption of data centers, as it reduces the need to cool the liquidcirculating through the cooling module 100. In some embodiments, theopening and closing of the dampers 512 and 514, and the operation of theceiling exhaust fans 516 are all controlled by an electronic device suchas a temperature control unit that monitors the temperature inside andoutside the server cooling room and operates the dampers and the fans toachieve optimal efficiency in cooling the room.

Depending on the location of the data center, humidity of the outsidecool air may vary. When the humidity of the outside cool air is low, theoutside air may have to be conditioned so that the humidity level meetsthe requirement for reliable operation of the servers. Although servermanufacturers have significantly relaxed the requirement on humidity forreliable operation of the server equipment, the appropriate humidity ofambient air inside a data center server cooling room still is importantto the performance and reliability of the equipment in a data center. Insome embodiments, one or more humidifiers may be installed in the mixingchamber 518 to condition the humidity of the air passing through themixing chamber.

FIG. 6 illustrates another example data center server cooling room 600with one or more ceiling exhaust fans 616, ceiling dampers 614 whichcontrols outside air intake, a mixing chamber 602, and dampers 612 thatcontrols circulation of hot air entering into the mixing chamber 602. Inthis embodiment, the cooling coils 604 are installed inside the mixingchamber 602. The mixing chamber 602 is connected to the cold rowencapsulation structure 606 via a connection enclosure 618. Server rackports 610 on the cold row encapsulation structure 606 are connected tothe server racks 608. The servers may be installed into the server racksto achieve a front-to-back airflow pattern. The front face of the serverracks 608 intersects the interior space of the cold row encapsulationstructure 606. The server fans inside the servers draw cold air from thecold row encapsulation structure 606 to cool the servers and eject hotair from the back of the server racks.

In this embodiment, the server cooling room may have two modes of airflow depending on the outside temperature. In one mode, outside cool airenters the mixing chamber 602 through the open ceiling dampers 614 andis conditioned by the cooling coils 604. In some embodiments,humidifiers may be installed in the mixing chamber 602 to add moistureto the outside air. The conditioned cold air enters the cold rowencapsulation structure 606 by gravity and generally lower pressureinside the interior space of the cold row encapsulation structure 606.The server fans in the servers installed on the racks draw the cold airfrom the cold row encapsulation structure 606 to cool the servers. Whenthe outside air is hot and not appropriate for cooling purposes, thesystem operates in another mode whereby the ceiling dampers are closedto prevent hot outside air from entering the mixing chamber 602. Thedampers 612, however, are open. Hot air inside the server cooling roomenters the mixing chamber through the dampers 612 and exchanges heatwith the cooling coils 604. In some embodiments, an electronic devicemonitors the temperature both inside and outside the server cooling room600 and may open or close dampers 612 and 614 and the ceiling exhaustfans 616 depending on the inside and outside temperature. The sameelectronic device may further monitor the humidity level of the air bothinside and outside the server cooling room and control the humidifiersthat may be installed inside the mixing chamber 602.

FIG. 7 illustrates a server cooling room 700 that is similar to the datacenter server cooling room shown in FIG. 6. The server cooling room 700,however, comprises multiple cooling modules 702 and multiple cold rowencapsulation structures 706, one or more ceiling exhaust fans 720, oneor more ceiling dampers 718, one or more mixing chambers 716 with one ormore dampers 724, and multiple server racks 710. The multiple coolingmodules 702 are connected to the mixing chamber 716 through enclosure722. Server rack ports 708 on the enclosure of the cold rowencapsulation structures 706 connect to the servers 710. The systemoperates in two modes as illustrated in FIG. 4. Air from the mixingchamber is cooled by the cooling coils 704 in each of the coolingmodules before entering each individual cold row encapsulation structure706.

FIG. 8 illustrates a server cooling room 800 with one mixing chamber 802and multiple cold row encapsulation structures 806. Cooling coils 804are installed in the mixing chamber 802. The system operates in twomodes as illustrated in FIG. 6. One or more ceiling dampers 818 may openor close depending on the temperature of the outside air. One or moredampers 816 may open or close to control hot air circulation inside theserver cooling room 800. The top surface of each of the cold rowencapsulation structures 806 is connected to the mixing chamber 802through enclosure 822. Air from the mixing chamber is cooled by thecooling coils 804 before entering each individual cold row encapsulationstructure 806 through the enclosure 822. However, unlike the servercooling room shown in FIG. 7, no individual cooling module is installedon top of each cold row encapsulation structure 806. The server rackports 808 on the enclosure of the cold row encapsulation structure 806are connected to the server racks 810. Servers may be installed into theserver racks 810 to achieve a front-to-back airflow pattern. The serverfans inside the servers draw cold air from each individual cold rowencapsulation structure 806 to cool the servers and eject hot air fromthe back of the server racks.

FIG. 9 illustrates yet another server cooling room 900 with multiplecooling modules 902 and multiple cold row encapsulation structures 906,one or more ceiling exhaust fans 920, one or more ceiling dampers 918,one or more mixing chamber 916 with dampers 914, and multiple serverracks 910. The system operates in two modes as illustrated in FIG. 8.However, unlike the server cooling room shown in FIG. 8, in addition tothe cooling coils 904 in each cooling module 902, there are one or morecooling coils 924 installed in the mixing chamber 916 as well. Thecooling modules are connected to one mixing chamber 916 throughenclosure 922. Air from the mixing chamber is cooled by the coolingcoils 924 in the mixing chamber 916 and is further cooled by each of thecooling modules 902 before entering each individual cold rowencapsulation structure 906.

The present invention has been explained with reference to specificembodiments. For example, while embodiments of the present inventionhave been described with reference to specific components andconfigurations, those skilled in the art will appreciate that differentcombination of components and configurations may also be used. Otherembodiments will be evident to those of ordinary skill in the art. It istherefore not intended that the present invention be limited, except asindicated by the appended claims.

1. A server cooling system, comprising an enclosure defining an interior space and comprising a server rack port configured to engage a rack; a cooling module operative to supply cooling air to the interior space defined by the enclosure from a top surface of the enclosure; and a rack including one or more rack-mounted-units installed therein, wherein the rack is engaged in the server rack port such that respective front faces of the one or more rack-mounted units interface with the interior space defined by the enclosure; and wherein at least one or more of the rack-mounted units comprises a cooling fan operative to draw air from the interior space.
 2. The server cooling system of claim 1 wherein the cooling module is mounted above the top surface of the enclosure.
 3. The server cooling system of claim 1 wherein the cooling fan is operative to eject air out of a back panel of the rack-mounted unit opposite the front face.
 4. The server cooling system of claim 1 wherein the rack comprises a panel covering a gap between a first rack-mounted unit and a second rack-mounted unit of the one or more rack-mounted units.
 5. The server cooling system of claim 1 wherein the enclosure comprises a first lateral face and a second lateral face opposing the first lateral face, and wherein the server rack port is defined in the first lateral face, and wherein the server cooling system further comprises a second rack port defined in the second lateral face, and a second rack including one or more rack-mounted-units installed therein, wherein the second rack is engaged in the second server rack port such that respective front faces of the one or more rack-mounted units interface with the interior space defined by the enclosure; and wherein at least one or more of the rack-mounted units comprises a cooling fan operative to draw air from the interior space.
 6. The server cooling system of claim 1 wherein the enclosure further comprises a door allowing access to the interior space.
 7. The server cooling system of claim 1 wherein the rack is removably engaged to the rack port.
 8. The server cooling system of claim 1 wherein the rack is integrally attached to the enclosure.
 9. The server cooling system of claim 1 wherein the server rack port comprises a gasket configured to substantially seal the rack in the server rack port.
 10. A server cooling system, comprising an enclosure defining an interior space and comprising a server rack port configured to engage a rack; a cooling module operative to supply cooling air to the interior space defined by the enclosure from a top surface of the enclosure; and a rack-mounted unit comprising a front face disposed to interface with the interior space defined by the enclosure and a cooling fan operative to draw air from the interior space through the front face.
 11. The server cooling system of claim 10 wherein the cooling module is mounted above the top surface of the enclosure.
 12. The server cooling system of claim 10 wherein the enclosure further comprises a door allowing access to the interior space.
 13. The server cooling system of claim 10 wherein the rack is removably engaged to the rack port.
 14. The server cooling system of claim 10 wherein the rack is integrally attached to the enclosure.
 15. The server cooling system of claim 10 wherein the server rack port comprises a gasket configured to substantially seal the rack in the server rack port.
 16. A server cooling system, comprising an inside space defined by a floor, four lateral walls, and a ceiling; an enclosure disposed within the inside space, wherein the enclosure defines an interior space and comprises a server rack port configured to engage a rack; a cooling module operative to supply cooling air to the interior space defined by the enclosure from a top surface of the enclosure; a rack including one or more rack-mounted-units installed therein, wherein the rack is engaged in the server rack port such that respective front faces of the one or more rack-mounted units interface with the interior space defined by the enclosure; and wherein at least one or more of the rack-mounted units comprises a cooling fan operative to draw air from the interior space and expel heated air to the inside space.
 17. The server cooling system of claim 16 further comprising one or more valved openings in the inside space whereby air inside and outside the inside space is exchanged, and a control system operably connected to the one or more valved openings to selectively activate the one or more valved openings based on temperatures observed within and outside the inside space.
 18. The server cooling system of claim 17 further comprising a mixing unit coupled to the one or more valved openings and the cooling module, wherein the control system is operative to cause the mixing module to receive either outside air through the one or more valved openings or air from the inside space based on temperatures observed within and outside the inside space.
 19. The server cooling system of claim 18 further comprising a second set of one or more valved openings defined in the mixing unit to control the flow of air from the inside space into the mixing unit.
 20. The server cooling system of claim 16 wherein the rack and the enclosure are mounted to the floor. 